If you’re interested in serial killers, you’ll be fascinated by the story of this former Canadian nurse who pleaded guilty last week to killing “mean” patients, believing it was what God wanted her to do.

Elizabeth Tracey Mae Wettlaufer, 49, was working at an assisted-living facility when she poisoned eight residents with lethal doses of insulin between 2007 and 2014. The victims ranged from 75 to 90 years old.

According to CNN, Wettlaufer told interrogators that she knew right from wrong, but that she was angry with life. She also claimed that she would get a “red surging with God telling me this is the one.”

She also attempted to kill other patients, but to no avail.

Wettlaufer’s confession tape shows her admitting that after her fifth victim, she began to doubt that God was telling her to kill, and that she thought it may be the devil instead. For a brief period of time, she stopped killing, though she later went on to kill three more patients.

While Wettlaufer confessed to a few friends and her pastor, she wasn’t caught until police received a tip in September about a nurse who was killing her patients.

Though Wettlaufer pleaded guilty, she won’t be sentenced till later this month and faces life in prison.